Geometrical Phase Optical Components: Measuring Geometric Phase without Interferometry

Oriol Arteaga,Hana Bendada

doi:10.3390/cryst10100880

Abstract

Optical components that are based on Pancharatnam–Berry phase feature a polarization-dependent diffraction that can be used to fabricate lenses and gratings with unique properties. In recent years, the great progress made in the fabrication of the metasurfaces that are required for these optical components has lowered their cost and has made them widely available. One of the often-overlooked properties of optical components based on geometrical phases (GPs) is that, contrary to dynamical phases, their phase can be measured while using a polarimetric technique without the need to resort to interferometry methods. This is possible because the Pancharatnam–Berry phase is not controlled by an optical path difference; it results from a space variant polarization manipulation. In this work, we apply Mueller matrix microscopy in order to measure the geometrical phase of GP lenses and polarization gratings. We show that a single space resolved Mueller matrix measurement with micrometric resolution is enough to obtain a full characterization phase-profile of these GP-based optical components and evaluate their performance.

Highlights

In the last years, the interest in the concept of “structured light”, which is light featuring a relatively complex spatial structure, has been continuously growing [1]
The propagation behaviour of light is determined by its wavefront structure, which can be controlled by the phase distribution introduced by optical elements as it happens for example with the simple refractive optical lenses, and in other more recently engineered optical elements, such as spatial light modulators, holograms, plasmonic or dielectric metasurfaces, etc. [2,3,4]
We focus on the study of geometrical phase (GP) optical elements, in which the wavefront structure of light is controlled by phase retardation, which can be made independent from the propagation length

Summary

Introduction

The interest in the concept of “structured light”, which is light featuring a relatively complex spatial structure, has been continuously growing [1]. The spatial structure affects only the intensity distribution of light, but a growing number of techniques and applications are based on controlling the phase and polarization distributions. We focus on the study of geometrical phase (GP) optical elements, in which the wavefront structure of light is controlled by phase retardation (birefringent effects), which can be made independent from the propagation length. Pancharatnam when studying the interference of polarized beams produced by crystal plates [5]. He noticed a phase shift arising when the polarization of a light was varied in a cyclic manner that corresponded to half of the solid angle subtended by the polarization cycle on the Poincaré sphere. The work of Pancharatnam went almost unnoticed and received little attention but, decades later, it gained the deserved recognition when M.V.Berry showed the equivalence

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Conclusion